bogging down

[spanker]

Hi All

Took my 125lc for mot this morning passed no problem so thought id go for a quick ride see how it is after so many years .

The bike has been restored the engine rebuilt not by me, and I have limited info. I don't think the engine has been used much its not run in yet from what I gather but I think its been started from time to time previously.

it starts and ticks over ok but when it reaches about 4-5k revs it just bogs down and doesn't go anywhere cant get it to rev over 6k.

ive took the plug out looks to be burning ok.

its had new fuel

all the pipes look connected in the right place.

air filter looks to be in good condition

any ideas were to start would be great

pic of spark plug

[spanker]

Mar 11, 2017 22:16:28 GMT 1 tony2stroke said:

That looks on the lean side to me, clean carb, take petrol tap off and clean filter that's attached to it inside the tank and the 1 in the fuel tap bowl would be my suggestion mate.

cheers will give it a go tomorrow

[spanker]

ok cleaned the tap filters seemed ok,flows fast enough.
taken carb of give it a clean blown all the jets out bit of crap in the float bowl and what looks like a drop of water nothing to drastic.

Anything else i should check while ive got the carb off? the main jet has 170 on it is this standard ?

thanks

[spanker]

Mar 12, 2017 11:57:28 GMT 1 tony2stroke said:

Mar 12, 2017 11:15:31 GMT 1 spanker said:

ok cleaned the tap filters seemed ok,flows fast enough.
taken carb of give it a clean blown all the jets out bit of crap in the float bowl and what looks like a drop of water nothing to drastic.

Anything else i should check while ive got the carb off? the main jet has 170 on it is this standard ?

thanks

Here is all the info you will ever need including a link to download a free Mikuni VM carb manual, Jet size depends on model ie 12A or 10w and the like, Make sure you take out the emulsion tube clean it and clean everything including pilot jet.

1 other thing make sure the tank breather is not blocked, I think its in the petrol cap

rdlccrazy.proboards.com/thread/7098/jetting-carbs

Thanks For the link, some good info
Ive removed cleaned the emulsion tube and all the other jets

the carb has 12a on it but the engine is a 10w i think, well thats on the side of the barrel.
(1gm)




the main jet is 170 standard is 195
for a 12a
the needle clip is currently is set at 3 from the top it should be 4 according to the link Ill try it on 4 see how that is

it says the air jet should be 2.5 is this the hole in back of the carb that the air screw adjusts? its not a brass jet?

sorry for all the questions

[wonkywheel]

That jet is too small for a 12A carb. The main jet operates from 3/4 throttle onwards.
What exhaust are you running and Is the bike restricted?

[spanker]

It has a micron fitted large can i think, it has bs au 193-t2 pcun-1 stamped on it
im not to bothered about the full power at mo just running reasonable will do.

its a bit strange with the jet size that's in it doesn't make sense from reading the info,it would make more sense if the carb was a 10w and had a micron fitted.



ill get a 195 jet and put the carb needle settings back to standard for a 12a.

thanks for all the help

[wonkywheel]

Mar 12, 2017 22:21:01 GMT 1 spanker said:

It has a micron fitted large can i think, it has bs au 193-t2 pcun-1 stamped on it
im not to bothered about the full power at mo just running reasonable will do.

its a bit strange with the jet size that's in it doesn't make sense from reading the info,it would make more sense if the carb was a 10w and had a micron fitted.



ill get a 195 jet and put the carb needle settings back to standard for a 12a.

thanks for all the help

With a Micron, it would be wise to go 2 sizes up from 195. Start there.

[spanker]

cheers guys will ill get some jets ordered

[bertiemollie]

Back in the day I ran a ledar kit, small can micron and K&N with a 220 main jet. You should be safe to start there. Remember to turn your oil up as adding more fuel with affect your oil mix ratio unless you are running premix of course.

Nice bike BTW. Best colours too ;-)

Here's mine.

[spanker]

haha Snap!
The new jets came yesterday I got a 220 and a 210 ive put the 220 one in, not had chance to test it as yet,its got a standard air box and i checked the oil pump and it looks to have been turned up a bit so hopefully should be ok. will try it this weekend if i get chance.
wonkywheel mentioned a ledar kit as the carb has an odd screw were a breather tube should be (another thread) but i think its just been jetted as a 10w carb which seems odd cos it clearly says 12a.

Fingers crossed

[spanker]

Finally got chance to take it out for a spin I removed the wood screw from the breather tube and fitted a breather elbow and pipe along with the 220 main jet and moved the needle clip to position 4, put a new plug in and did about 50 miles. it revs much better than before, it is sluggish until about 7k then off she goes.
just took it easy really as its still running in but much better then previous.
this is what the new plug br8es looked like after the 50 miles

is it still a bit lean? do need a bigger jet?

[spanker]

sorry about the picture quality

[wonkywheel]

Mar 24, 2017 17:47:55 GMT 1 spanker said:

Finally got chance to take it out for a spin I removed the wood screw from the breather tube and fitted a breather elbow and pipe along with the 220 main jet and moved the needle clip to position 4, put a new plug in and did about 50 miles. it revs much better than before, it is sluggish until about 7k then off she goes.
just took it easy really as its still running in but much better then previous.
this is what the new plug br8es looked like after the 50 miles

is it still a bit lean? do need a bigger jet?

Hi again,
Good news the little single is beginning to rev out.
The plug looks too lean.
In theory going up in jet sizes should help.
As said, I'm no carb guru. Air/fuel ratio can affect running- hence why some engines run better without the standard air box and filter. Hence K&N filter and Ledar Kit.
When you fit a performance pipe, you will lose bottom end- thus take-off at 7K
Every engine reacts different to a performance pipe.